In the following link there is an element that has a facebook, twitter and youtube buttons, I would like to know how it's called and if there is a plugin that has it.
It doesn't have a dedicated name but people call it social sidebar / social bar / social media icons.
There are many pens available online which can be used directly with or without modifications:
Just take a look and google "social sidebar codepen" you will get many options.
I hope this'll help you :)
Those are Social Media Buttons or Social Sharing buttons. I would call the elements in this specific example "Expanding Social Sharing Buttons".